The present invention relates to a technology for estimating the reusability of the three-dimensional CAD (Computer-Aided Design) data. In addition, the present invention relates to a technology for estimating the modeling skill of the CAD system operator.
When generating the CAD data of the design object using the three-dimensional CAD system, there are several modeling methods to be applied to an identical design shape. In case of generating the CAD data for the design shape shown in FIG. 16, several variations for the modeling method are described. As one of the methods for generating the CAD data of the design shape shown in the figure, as shown in FIG. 17, (a) the cross-section is defined as a closed geometric figure, and this closed geometric figure is made to rotate in the center line at first, and next (b) the design shape is generated by removing the bolt hole by subtraction operation. As another method, as shown in FIG. 18, the same design shape can be generated by means that (a) the cylinder corresponding to the flange is defined, (b) the cylinder on the axis is defined and a unified body is defined by add operation of the flange and this axial cylinder, (c) a hole is removed by subtraction operation, and (d) the bolt hole is removed by subtraction operation.
As described above, there are alternative modeling methods for generating the CAD data for an identical design shape, and the difference in the modeling methods has influence on the easiness for modifying the model. For example, in case of modifying the circular shape of the hole shown in FIG. 16 to a rectangular hole, the closed geometric figure shown in FIG. 17 (a) should be modified in the modeling method in FIG. 17. On the other hand, in the modeling method in FIG. 18, the target figure shown in FIG. 19 can be obtained only by removing the hole at Step (c) with the rectangular cylinder to be used for subtraction operation instead of using the circular cylinder.
There arise many design modifications in the design process for the actual products. In the design process, the easiness in modifying the model may contribute to the design productivity. In addition, in applying the existing components to new products, it may contribute to the design productivity that the components to be applied properly are retrieved and their three-dimensional CAD data can be modified. However, as shown in FIGS. 17 and 18, the modification complexity and its man-hour depends upon the modeling methods very much. The man-hour for the overall modeling process can be reduced by generating the CAD data by the modeling method with its modification complexity being lower.
The selection of the modeling method for the CAD data depends upon the skill of the CAD system operators. The operator having a higher skill can select such a modeling method as being adequate for reusing the CAD data and generate the model which can be easy for modification. However, the operator having a lower skill may have an inclination to select such a modeling method as shown in FIG. 17 and thus, may generate the model which may be difficult for reuse.
In the prior art, major methods for estimating the modeling method trace the modeling history and the feature structure of the model by using the CAD system. As for the estimation system using computers, there is such method for estimating whether the selected method is compliance with the exceptional conditions for modeling and users' criteria by verifying the predefined check items individually or verifying their combinations.
In the method in which the modeling history and its feature structure are estimated manually by the operator with the CAD system, it is required to read in the individual CAD data into the CAD system and their feature structure should be estimated. In case that the design object includes complex shapes and the large volume of CAD data is estimated, there is such a problem that the man-hour for estimation work becomes too large.
And furthermore, in the estimation systems in which the predetermined items are verified, as only the check items related directly to the exceptional conditions and the modeling criteria can be estimated, there is such a problem that the applicable models and the supported check items are limited.